1. Field of the Invention
The present invention generally relates to an angle correcting method, and more particularly to an inclined angle correcting method on the border of a tablet.
2. Description of the Prior Art
Various touch sensitive inputting devices, such as the Tablet PCs, incorporate a computer display to perform sensing technology. The device detects the position of a position pointer or a touched sensing surface by a finger to generate the corresponding coordinates, and further interact with a computer device. The common sensing devices utilize various sensing technology such as resistive, capacitive, or optical sensing technology to perform sensing.
Please refer to FIG. 1, which shows a schematic diagram of a conventional electromagnetic touch sensitive device (abbreviated as the touch sensitive device hereinafter). The touch sensitive device 1 is operated with an electromagnetic pointer device 2. The touch sensitive device 1 includes a display panel 11 and an inductive loops layer (not shown). The inductive loops layer is disposed under the display panel 11 to induce the electromagnetic signal transmitted from the electromagnetic pointer device 2. When the electromagnetic pointer device 2 is approached the display panel 11 and transmits the electromagnetic signal, these inductive loops will determine the information such as written position, trace, or pressure according to the received electromagnetic signal. However, because the display panel 11 is disposed between the inductive loops layer and the electromagnetic pointer device 2, and the display panel 11 has a depth itself, it results in a refraction angle between the inductive loops layer and the electromagnetic signal transmitted from the electromagnetic pointer device 2. Therefore, a parallax between the positions of the cursor and pen point of the electromagnetic pointer device 2 may be generated. The more leaning the electromagnetic pointer device 2 is or the more depth the display panel 11 has, the more parallax between the cursor and pen point of the electromagnetic pointer device 2 it generates.
In view of forgoing, it must incorporates with the mechanism for detecting the inclined angle of the electromagnetic pointer device 2 when designing the touch sensitive device 1, thereby adjusting or compensating the trace position displayed according to the inclined angle. Please moreover refer to FIG. 2, which shows the variation of the magnetic field induced by the electromagnetic pointer device 2. When the electromagnetic pointer device 2 approaches the display panel 11 perpendicularly, the electromagnetic signal in the position X−5-X5 will be induced as shown in FIG. 2. Wherein, it has the strongest electromagnetic signal in the position X0 nearest to the pen point of the electromagnetic pointer device 2. The intensity of the electromagnetic signal may be decreased progressively and symmetrically toward around. The inclined angle of the electromagnetic pointer device 2 can be determined by computing the ratio of the voltage values of the strongest electromagnetic signal induced in the position X0 to the electromagnetic signal inducted in the position X−5 or X5.
When the electromagnetic pointer device 2 approaches the display panel 11 at point A, the inclined angle can be determined according to above method. However, it can not work when the electromagnetic pointer device 2 approaches at point B which is located on the border of the display panel 11. The inductive loops layer could not induct the voltage value on the right side (about the position X4 or X5) near the border of the display panel 11, thereby the inclined angle can not be determined effectively.